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/*
* i2c-algo-sgi.c: i2c driver algorithms for SGI adapters.
*
* This file is subject to the terms and conditions of the GNU General Public
* License version 2 as published by the Free Software Foundation.
*
* Copyright (C) 2003 Ladislav Michl <ladis@linux-mips.org>
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/errno.h>
#include <linux/delay.h>
#include <linux/i2c.h>
#include <linux/i2c-algo-sgi.h>
#define SGI_I2C_FORCE_IDLE (0 << 0)
#define SGI_I2C_NOT_IDLE (1 << 0)
#define SGI_I2C_WRITE (0 << 1)
#define SGI_I2C_READ (1 << 1)
#define SGI_I2C_RELEASE_BUS (0 << 2)
#define SGI_I2C_HOLD_BUS (1 << 2)
#define SGI_I2C_XFER_DONE (0 << 4)
#define SGI_I2C_XFER_BUSY (1 << 4)
#define SGI_I2C_ACK (0 << 5)
#define SGI_I2C_NACK (1 << 5)
#define SGI_I2C_BUS_OK (0 << 7)
#define SGI_I2C_BUS_ERR (1 << 7)
#define get_control() adap->getctrl(adap->data)
#define set_control(val) adap->setctrl(adap->data, val)
#define read_data() adap->rdata(adap->data)
#define write_data(val) adap->wdata(adap->data, val)
static int wait_xfer_done(struct i2c_algo_sgi_data *adap)
{
int i;
for (i = 0; i < adap->xfer_timeout; i++) {
if ((get_control() & SGI_I2C_XFER_BUSY) == 0)
return 0;
udelay(1);
}
return -ETIMEDOUT;
}
static int wait_ack(struct i2c_algo_sgi_data *adap)
{
int i;
if (wait_xfer_done(adap))
return -ETIMEDOUT;
for (i = 0; i < adap->ack_timeout; i++) {
if ((get_control() & SGI_I2C_NACK) == 0)
return 0;
udelay(1);
}
return -ETIMEDOUT;
}
static int force_idle(struct i2c_algo_sgi_data *adap)
{
int i;
set_control(SGI_I2C_FORCE_IDLE);
for (i = 0; i < adap->xfer_timeout; i++) {
if ((get_control() & SGI_I2C_NOT_IDLE) == 0)
goto out;
udelay(1);
}
return -ETIMEDOUT;
out:
if (get_control() & SGI_I2C_BUS_ERR)
return -EIO;
return 0;
}
static int do_address(struct i2c_algo_sgi_data *adap, unsigned int addr,
int rd)
{
if (rd)
set_control(SGI_I2C_NOT_IDLE);
/* Check if bus is idle, eventually force it to do so */
if (get_control() & SGI_I2C_NOT_IDLE)
if (force_idle(adap))
return -EIO;
/* Write out the i2c chip address and specify operation */
set_control(SGI_I2C_HOLD_BUS | SGI_I2C_WRITE | SGI_I2C_NOT_IDLE);
if (rd)
addr |= 1;
write_data(addr);
if (wait_ack(adap))
return -EIO;
return 0;
}
static int i2c_read(struct i2c_algo_sgi_data *adap, unsigned char *buf,
unsigned int len)
{
int i;
set_control(SGI_I2C_HOLD_BUS | SGI_I2C_READ | SGI_I2C_NOT_IDLE);
for (i = 0; i < len; i++) {
if (wait_xfer_done(adap))
return -EIO;
buf[i] = read_data();
}
set_control(SGI_I2C_RELEASE_BUS | SGI_I2C_FORCE_IDLE);
return 0;
}
static int i2c_write(struct i2c_algo_sgi_data *adap, unsigned char *buf,
unsigned int len)
{
int i;
/* We are already in write state */
for (i = 0; i < len; i++) {
write_data(buf[i]);
if (wait_ack(adap))
return -EIO;
}
return 0;
}
static int sgi_xfer(struct i2c_adapter *i2c_adap, struct i2c_msg *msgs,
int num)
{
struct i2c_algo_sgi_data *adap = i2c_adap->algo_data;
struct i2c_msg *p;
int i, err = 0;
for (i = 0; !err && i < num; i++) {
p = &msgs[i];
err = do_address(adap, p->addr, p->flags & I2C_M_RD);
if (err || !p->len)
continue;
if (p->flags & I2C_M_RD)
err = i2c_read(adap, p->buf, p->len);
else
err = i2c_write(adap, p->buf, p->len);
}
return err;
}
static u32 sgi_func(struct i2c_adapter *adap)
{
return I2C_FUNC_SMBUS_EMUL;
}
static struct i2c_algorithm sgi_algo = {
.master_xfer = sgi_xfer,
.functionality = sgi_func,
};
/*
* registering functions to load algorithms at runtime
*/
int i2c_sgi_add_bus(struct i2c_adapter *adap)
{
adap->id |= I2C_ALGO_SGI;
adap->algo = &sgi_algo;
return i2c_add_adapter(adap);
}
int i2c_sgi_del_bus(struct i2c_adapter *adap)
{
return i2c_del_adapter(adap);
}
EXPORT_SYMBOL(i2c_sgi_add_bus);
EXPORT_SYMBOL(i2c_sgi_del_bus);
MODULE_AUTHOR("Ladislav Michl <ladis@linux-mips.org>");
MODULE_DESCRIPTION("I2C-Bus SGI algorithm");
MODULE_LICENSE("GPL");
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